dude you must or get rid of her
I would try to bring it up in a conversation so she can deflect it more easily. I don't think she will, but that would be much better than trying to just suddenly lock lips with her.
Make a move, so you make a fool of yourself. No big deal, we all have. Just do it. You may succeed on the other hand.
That gives you an easy way to let her know it bothers you and that you're interested! Next time she does say something like "I've got to admit that I'm feeling jealous when you bring him up." An overture like that would be the best way. (well, me being a dateless wonder might make that suspect, hahaha)
Just do it, dumbass.
If she stops you, shrug and move on.
DON'T apologize, but DO back off if she draws a line in the sand.
It's only as awkward as you are. If you shrug it off as "oh well I was horny and thought I'd try" she'll be fine with it. Especially if you don't apologize and look at her like she's crazy if she takes offense. Trust me on this one. The only way it'll screw anything up is if she feels the same way but is in denial (which you can work with) or if she's a psycho *****.
I'm 90% certain she's wondering why you haven't already. :P